| <refentry id="vidioc-querystd"> |
| <refentrytitle>ioctl VIDIOC_QUERYSTD</refentrytitle> |
| <refname>VIDIOC_QUERYSTD</refname> |
| <refpurpose>Sense the video standard received by the current |
| <funcdef>int <function>ioctl</function></funcdef> |
| <paramdef>int <parameter>fd</parameter></paramdef> |
| <paramdef>int <parameter>request</parameter></paramdef> |
| <paramdef>v4l2_std_id *<parameter>argp</parameter></paramdef> |
| <term><parameter>fd</parameter></term> |
| <term><parameter>request</parameter></term> |
| <para>VIDIOC_QUERYSTD</para> |
| <term><parameter>argp</parameter></term> |
| <title>Description</title> |
| <para>The hardware may be able to detect the current video |
| standard automatically. To do so, applications call <constant> |
| VIDIOC_QUERYSTD</constant> with a pointer to a &v4l2-std-id; type. The |
| driver stores here a set of candidates, this can be a single flag or a |
| set of supported standards if for example the hardware can only |
| distinguish between 50 and 60 Hz systems. When detection is not |
| possible or fails, the set must contain all standards supported by the |
| current video input or output.</para> |